We propose to use the fluorescence-activated cell sorter (FACS) to detect and isolate fetal cells that pass into the maternal circulation during gestation. Fetal cells bearing paternal HLA antigens will be stained with heterologous anti-HLA antibodies and sorted on the FACS. The presence of Y-body containing male cells, detected by quinacrine staining of sorted cells, in pregnancies where the fetus is male, will be used to assess success. We will also examine fetal cell frequencies in the maternal circulation at various times of gestation and the nature of the fetal cell. We will develop other antibodies which may be useful for identifying fetal cells such as anti-H-Y and monoclonal antibodies to HLA or fetal cell-specific antigens produced by myeloma hybrids (hybridomas). To try to induce the fetal cells to divide so that karyotypes can be made, various lymphocyte mitogens and growth factors for other hematopoietic cells will be used. For lymphocytes these include phytohemagglutinin, conconavalin A, staph protein A, pokeweed mitogen for lymphocytes in combination with putative growth factors from such sources as monocytes and mixed lymphocyte cultures. For other hematopoietic cells, placental growth factors, erythropoietin, conditional media from growth of various other cells will be tried. This project may lead to non-invasive methods for prenatal diagn sis of chrom some abnormalities and other genetic diseases.